Sunday, June 24, 2007

How DNA probe assay works?



How DELFIA DNA probe assays work


DELFIA DNA probe assays are based on oligonucleotide probes labeled with lanthanide chelates, solid phase capture and measurement by time-resolved fluorometry.

Assays are performed in microtitration format, and the availability of different lanthanides (Eu, Tb, Sm, and Dy) enable multiplexing up to quadruple analysis in a single assay well.


A typical DELFIA DNA probe assay is the research assays for investigation of genes involved in predisposition to celiac disease, shown below. In this assay three different labels are used and two wells are required for each determination.



Saturday, June 16, 2007

Q&A GM FOOD

What are Genetically Modified Crops?

Genetically Modified Crops are foods that have had a gene extracted from a living thing, which has been placed into a different food by a scientist. This creates plants that Nature never could.

What is the purpose for Genetic Modification?

Genetically Modified Crops are made for many different purposes, the main one being to create a food able to survive being sprayed with harmful chemicals like pesticides and herbicides.Other purposes are to make food stay fresher for longer, to kill pests, to produce more of the crop and to experiment with taste and quality.

What is Gene Technology?

Gene Technology is one type of modern Biotechnology. It is the use of living things to make or change products, such as the foods we eat.
Here are interactive explanations of DNA, a gene probe and gene splicing.

What crops are produced through Genetic Modification?

The first genetically modified crops to be sold in the USA were tomatoes, which were modified so they wouldn't go soft so quickly, then soya beans and oilseed rape, which gives margarine and oils. They were modified to survive certain herbicides and weed-killers, then maize and cotton were modified to carry a poison that kills pests and protects crops against damage. Potatoes were also some of the earliest vegetables to be modified.

What are the benefits of Genetic Modification?

- The agricultural process is kinder to the environment, by using less pesticides, fertilizers and water.
- Without gene technology, Australia would not be able to maintain its role as an agricultural producer. There would therefore be a loss of jobs and food prices, imports and interest rates would go up.
- Gene technology is one of the best solutions to the problem of world hunger. It can increase production and lower the cost of food.
- Gene modification can boost immunity and develop inbuilt vaccines for livestock and poultry.
- Gene technology can remove lactose, so that lactose-intolerant people can eat dairy products.
- Crops could be grown in areas suffering from drought and salt.
- GM crops are faster and cheaper.
- Many vegetarians may fid they are now able to consume products which have synthetic, rather than animal-based, origins.
- G M Foods are sometimes thought as being more nutritious, tasting better and they keep longer.
- Many people rely on genetically modified foods for medicines, for example insulin for diabetics.
Proven by research, GM Foods are safe.

What are the disadvantages of Genetic Modification?

- Most food manafacturers are unable (or unwilling to provide information on whether or not their products contain GM ingredients. This means you rarely know what you are eating.
- GM crops can contaminate other crops simply by pollen being blown by wind from one field to another.
- World starvation has more to do with wealth distribution rather than the inadequate production of foods.
- Sometimes GM crops have allergenic effects.
- Loss of nutritional value.
- Reduction of the efficiency of antibiotics.
- New viruses could evolve from the mass production of GM crops.
- The more that gene technology is used, the worse the environment will become.
- Pests may develop resistance to GM crops that have been designed to kill them.
- Humans do not have the right to genetically alter nature for their own convienience and profit.
- GM crops produce religious complications.
- Vegetarians and Vegans may find it offensive to put animal genes into plants.
- GM crops may cause harm to the wealth and welfare of animals.
- Some countries will not be able to afford GM foods.
- GM crops may produce ecological side effects (Monarch butterfiles).
- Too much money spent on Gene Technology could have been spent on other things.
- No assurances of public liability for Farmers of GM crops.

How does it affect society today and in the future?

Genetic modification is an issue which arises every day, although people are not always aware of it. At the moment there is a lot of debate whether GM foods are good or bad. GM Crops are affecting society in many of the foods that we buy. The most common foods are maize, cotton, tomatoes, potatoes, corn, canola, soybean and sugar beet. These food items can be found in bread, pasta, chips etc. There are laws which enforce the clear labelling of GM food on the ingredients list which is helping the consumers of our society choose what they buy

Genetic Engineering

Myths on GM Foods

Myth No. 1
Genetic engineering (GE) is not new. It is just the same as speeded-up selective breeding.

FACT
Genetic engineering (GE) and conventional breeding are worlds apart. Breeding does not manipulate genes; it involves crossing of selected parents of the same or closely related species. In contrast, GE involves extracting selected genes from one organism (e.g. animals, plants, insects, bacteria) and/or viruses, or synthesising copies, and artificially inserting them into another completely different organism (eg. food crops). GE usually employs virus genes to smuggle in and promote the inserted genes, and antibiotic resistance genes to act as markers. All these inserted genes are present in every cell of the plant.

Myth No. 2
Genetic engineering is precise.

FACT
The function of only a small proportion of the DNA in a higher organism is known. Modern genetics has shown that genes do not operate in isolation. Rather they interact in a complicated way, changing their behaviour in response to influences from other genes. Although a gene can be cut out precisely from the DNA of an organism, its insertion into the DNA of another organism is entirely random. This results in the disruption of the order of the genes on the chromosome and may result in random and unexpected changes in the functioning of the cells. Richard Lewontin, Professor of Genetics at Harvard University, has said of GE: "We have such a miserably poor understanding of how the organism develops from its DNA that I would be surprised if we don't get one rude shock after another."

Myth No. 3
GE foods vary from non-GE foods only in the characteristic that has been modified.

FACT
The random insertion of foreign genes into the genetic material may cause unexpected changes in the functioning of other genes. Existing molecules may be manufactured in incorrect quantities, at the wrong times, or new molecules may be produced. GE foods and food products may therefore contain unexpected toxins or allergenic molecules that could harm our health or that of our offspring.

Myth No.4
GE food is extensively tested and the GE food at present on our supermarket shelves is perfectly safe to eat.

FACT
No GE food testing is done in New Zealand. We rely almost entirely on the testing carried out by the GE biotechnology companies that have spent billions of dollars developing the food and intend to make a profit selling it to us. There are serious doubts about the adequacy of the testing and the validity of the conclusions drawn from the results. Independent long-term testing is required before we can be sure that GE food is safe to eat. Another health concern is the possible acceleration of the development of bacterial resistance to antibiotics due to the use of antibiotic resistance genes in the production of GE foods.

Myth No. 5
Genetically engineered food has improved nutritional value.

FACT
No GE food produced to date has been shown to be more nutritious than non-GE food. Most GE crops are only designed to be resistant to specific herbicides, to produce their own insecticides or to have an increased shelf life.

Myth No.6
One can always choose not to eat GE food.

FACT
At present most foods on New Zealand supermarket shelves containing GE ingredients are not labelled, so there is no way of knowing whether we are eating them. GE products are likely to be found in foods containing the following ingredients: Soya flour and oil (in many common foods including breads, sausages, etc.); Lecithin (in chocolate, ice cream etc.); Canola oil and Corn (maize) extracts.

Myth No. 7
Farmers will benefit from growing GE crops.

FACT
Seeds of genetically engineered crops are more expensive than those of conventional crops. Farmers in the UK and USA report that yields are generally no better, the crops are less reliable and overall have not improved profitability. Non-GE crops now receive a premium and as more countries reject GE foods, the opportunities to sell GE produce overseas are diminishing. Because of risks associated with GE crops insurance companies in the USA and UK are now reluctant to insure them. Farmers growing GE crops have to sign binding contracts with the biotechnology producers. These commit them to using only the herbicides produced by that company and prohibit them from the traditional practice of saving seed for the next season. Most third world farmers certainly will not benefit.

Myth No.8
GE crops will reduce the use of herbicides and pesticides.

FACT
Crops engineered to be resistant to specific herbicides may encourage more liberal use of those herbicides. This has been anticipated by one manufacturer, who has applied to ANZFA (Australia & New Zealand Food Authority) to have the allowable residue of the herbicide glyphosate (Roundup®) in foods sold in New Zealand increased by 200 times. In areas of the USA where crops engineered to produce their own insecticide are grown, pesticide use has not decreased.

Myth No. 9
There is no evidence that GE crops are harmful to the environment.

FACT
Insects, birds and the wind carry genetically altered pollen and seeds into neighbouring fields and far beyond. Cross-pollination occurs between GE crops and non-GE crops and their wild relatives. In this way resistance to weed killer, for example, might be transmitted to weeds making them more difficult to control. There is evidence that crops engineered to produce their own insecticide can kill beneficial insects.

Myth No. 10
GE crops will save the world from famine.

FACT
A major cause of famine is the unequal global distribution of food. Food mountains exist in much of the western world and food is regularly dumped. Poor people have limited ability to buy either GE or non-GE food. There is no evidence that GE crops produce higher yields than conventional crops or that GE products will be cheaper.

Myth No. 11
You can trust the scientists that GE food is good for you and the world.

FACT
The money for scientific research on GE here and overseas comes from either the biotechnology companies or the government. Both are committed to the promises of biotechnology. This means that even when scientists have concerns about the safety or commercial application of the technology, it is often hard for them to risk their careers by being openly critical. One respected scientist in the UK who spoke up about his experimental results showing damaging effects of feeding rats on a type of genetically engineered potato was immediately fired from his job.

Myth No. 12
You can't stop progress.

FACT
No of course we can't; and why would we want to? Progress implies change for the better. Change for the worse is regression. We must be sure that GE products have benefits for the consumer and are safe if they are to be introduced into our foods. We must not commit ourselves to a dubious technology that cannot be reversed.

Myth No. 13
There are more important things to worry about than GE foods.

FACT
Many scientists don't think so.For example Joseph Rotblat, the British physicist who won a 1995 Nobel Prize says: "My worry is that other advances in science may result in other means of mass destruction, maybe more readily available even than nuclear weapons. Genetic engineering is quite a possible area, because of these dreadful developments that are taking place there."

Link:
http://www.prorev.com/genetic.htm

Wednesday, June 13, 2007

Common Q asked

Common Questions asked about GM food

1. How long have GM foods been on the market?

The application of modern biotechnology in food production was started in the 90s. The first GM whole food, FLAVR SAVRTM tomato, was marketed in the United States in 1994.

2. What are the most common GM food ingredients or food products in the market?

The most common GM foods currently available in the market are soya bean and corn. Soya beans can be further processed into soy oil, soy flour to make food items such as pastries, edible oil and other soy products. Corn can be further processed into corn oil, flour or syrup to make food items such as snacks, bakery products and soft drinks.

3. Which countries are the major producers of GM foods?

The major producers of GM crops/foods are the United States, Argentina, Brazil and Canada.

4. How to identify GM foods in the market?

Basically, physical appearances of most GM foods are similar to their conventional counterparts. Biochemical analyses such as Polymerase Chain Reaction (PCR) or Enzyme Linked Immunosorbent Assay (ELISA) are ways to differentiate them.

5. Is it possible that GM foods currently available contain animal genes?

There is no GM crops currently on sale containing animal genes. To the best of our knowledge, the GM animals are still in the research stage and may be released in the future. Nevertheless, these products are subjected to stringent safety assessments by the industry and food authorities of the place of origin before they are available in the market.

6. What are the major concerns of green and consumer groups?

The major concern of green groups is the possible environmental impacts of GM crops. The major concern of consumer groups, as well as some green groups, is consumers' "right to know" hence the advocating of labelling of GM foods.

7. Will the development of herbicide-resistant crops actually increase the use of herbicide by farmers?

In general, herbicide-resistant crops will reduce the use of herbicides. The herbicide-resistant crops are usually resistant to "new generation" herbicides that are less toxic and less persistent in the environment. The development of crops with resistance to these herbicides may increase the use of these "new generation" herbicides but may at the same time decrease the use of herbicides that are more persistent in the environment. Nevertheless, the use of herbicides would be assessed by international authority to ensure that human health is not adversely affected.

8. What is GM salmon? Are they available in local markets?

GM salmon was developed to grow fast. In some study, this is accomplished by adding a growth hormone gene from another species of salmon and promoter gene from ocean pout for keeping the growth hormone gene constantly producing the hormone.

GM salmon is not available for sale worldwide. In the United States (US), the potential impacts of GM salmon on the ecosystem and any potential ill effects in human upon consumption are being assessed by the US agencies. GM salmon will not be placed in the markets until a full safety assessment on the product has been made.

9. Is GM food safe to eat?

World Health Organization (WHO) has pointed out that GM foods currently available on the international market have passed risk assessments and are not likely to present risks for human health. In addition, no effects on human health have been shown as a result of the consumption of such foods by the general population in the countries where they have been approved.

10. Are there any harmful effects associated with the consumption of GM food in human being?

No harmful effects have been reported in humans following the consumption of approved GM food.

11. Will GM foods elicit any allergic responses upon consumption?

Allergenicity is associated with many conventional foods including nuts and seafood. When new genes are introduced, there is a theoretical possibility that new allergens may be expressed in the food. However, allergenicity is included in the safety assessment of GM foods before the products are launched on the market. The assessment focuses on the source of the gene and the properties of proteins expressed by the gene. Such assessments could help to exclude GM foods that are likely to be allergenic from entering the market.

12. Has there been any GM food withheld from entering the market as a result of failing the allergenicity assessment?

A trial was conducted in 1996 to improve the nutritional content of soya bean, which has low content of methionine - an essential amino acid. It involved inserting a gene from Brazil nut to achieve high methionine content. Since Brazil nuts are allergenic to some people, the trial included screening for this side effect and found that the soya bean contained an allergen from Brazil nuts. The development of this soya bean was then stopped, thus this soya bean was never commercialised. This example illustrated the effectiveness of the safety assessment system in protecting public health.

13. What are the differences between genetic modification and traditional breeding? Are foods derived from genetic modification less safe than those derived from traditional breeding?

Traditional breeding has long been used in agriculture to obtain desirable characteristics of plants. This process may involve random transfer of thousands of genes and take many years to produce the desired characteristics. Genetic modification techniques allow the introduction of one or more of the desired genes to be introduced precisely into the host organism for the development of specified features. Marketed GM food has not been shown to be less safe than those obtained from traditional cross breeding techniques.

14. Why do GM foods contain antibiotic resistance genes? Do these genes affect human health?

In the process of genetic modification, antibiotic resistance genes are used as markers for identification of successful gene transfer. There are concerns about the possibility of transferring these genes from GM foods to bacteria in the human gut and resulting in the development of antibiotic resistance in these bacteria. Such gene transfer is considered a rare possibility because many complex and unlikely events would need to occur consecutively for this to happen. Nevertheless, the present trend is to avoid the use of antibiotics-resistance genes by switching to other alternatives. The World Health Organization and the Food and Agriculture Organization have also advised the industry not to use marker genes carrying information of resistance to antibiotics that are frequently prescribed for therapeutic purposes.

15. Are we already consuming GM food?

Genetically modified soya bean and corn, which have been approved in many countries including the US, Canada, Australia and member countries of the European Union, have been incorporated in different processed foods. All GM foods are considered as safe for consumption when they are approved for sale in marketplace. They are subjected to safety assessments by the industry and regulatory agencies of their places of origin before they can be placed in the market.

16. What is StarLink corn? What are the risks associated with StarLink corn? Are there any StarLink corn products in Hong Kong?

StarLink corn is a genetically modified corn, which contains a Bt protein (Cry9C protein). StarLink corn was developed by Aventis CropScience for the control of pests.The United States Environmental Protection Agency approved the use of StarLink corn for animal feed and industrial uses but not for human food use. This decision was made since the authority could not exclude the possibility of Cry9C protein in causing allergy. In September 2000, StarLink products were found in corn chips intended for human consumption. It was thought to be due to a breakdown of the channeling systems in the U.S. which normally segregated animal feed from human food. A search in Hong Kong showed that limited amount of the US recalled products were available. They were recalled by the local retailer. There was no report of persons falling ill after the consumption of those potential StarLink containing products in Hong Kong.

17. Are there international testing standards for GM foods?

To facilitate consumers' choice, a number of countries including the EU, Australia and Japan have instituted labelling requirement for GM foods. Threshold level for ingredients containing GM material is generally set in the respective regulations.
Laboratory techniques are also being developed to meet the increasing needs of testing and verification. However, there is no international consensus on laboratory testing methods on GM food. The Codex Committee on Method of Analysis and Sampling of the Codex Alimentarius Commission (Codex) is still working on the standardisation of GM food testing method.
Link:

What do you need to know about GM foods


Genetic modification or genetic engineering is one technology within a broader science known as biotechnology. This biotechnology includes a collection of scientific techniques that are used to create, improve or modify plants, animals and microorganisms.
The process can be carried out by intact organisms such as yeast or bacteria or by natural substances, such as enzymes from organisms. Some of these techniques date back hundreds of years.

The ancient Egyptians used yeast to make bread dough rise, and to ferment grape juice to produce wine. In the 1860s, Louis Pasteur improved the wholesomeness of milk by heating it to kill off harmful bacteria. The use of bacteria and molds to make cheese is also defined as biotechnology.

For centuries, crop and livestock breeders have used conventional techniques, such as selective breeding, cross pollination and natural mutations, to improve plants and animals for human benefit. They studied the characteristics of plants and animals that were easy to observe or measure, and made selections for better quality, higher yield, improved taste or pest and disease resistance. Most of these traits depend on the information contained in the DNA within genes, which is what is crossed when animals or plants are bred.

Techniques to analyze DNA, developed within the last twenty years, enable breeders to locate specific DNA chromosome regions that correspond to particular production traits. Breeders can now use these techniques to quickly and accurately choose superior individual plants or animals to breed, speeding the process of genetic improvement.

In the 1970s a new type of biotechnology, called genetic engineering, was developed, which allowed scientists to produce desired traits even more quickly and in a more predictable manner. This technique combined biochemistry and molecular biology and involved the modification of genes within an organism or the transfer of specific genes between organisms.

The location, timing and amount of gene expression can all be controlled by genetic modification. This may be achieved by the transfer of a gene from one organisms to another (transgenics) or by the modification of a gene within an organism.

In the genetic modification process, a specific gene with a desired trait is identified, isolated and removed from one organism. The gene is placed into a bacterial cell and reproduced. Then the copied gene is studied using molecular techniques to verify that the replicated gene carries the desired trait.

Once the gene is verified, it may be relocated into the DNA of another organism to replicate the desired trait, or it may be modified within the original organism to alter characteristics. The "genetically modified organism" then makes new substances or performs new functions based on its new DNA.

Genetic modification can improve the ability of an organism to do something it already does. An adjustment in the amino acid balance in a particular corn variety improves its storage ability. It can suppress or stop an organism from doing something it currently does.


Genetically modified organisms are extensively researched and tested, and safety information is reviewed by regulatory agencies in countries where these products are grown or imported.
Three agencies in the U.S., the USDA, EPA and FDA, are responsible for regulation and testing. The USDA is the lead agency regulating the safe field-testing of genetically-enhanced new plant varieties. In order to receive permission to test a new biotech plant, an applicant must provide information about the plant, including all new genes and gene products, their origin, the purpose of the test, how it will be conducted, and specific precautions to prevent the escape of pollen or plant parts from the field test site. Impact on the environment, on endangered or threatened species, and "non-target" species are also considered.

The EPA has authority over all new pesticides, including genetically-enhanced plants which produce their own protection against pests. In deciding whether to register a new product, the EPA considers human safety, impact on the environment, effectiveness on the targeted pest, and any effects on other "non-target" species, including endangered or threatened species.
Legal authority for food labeling rests with the FDA.
Foods derived from biotechnology must be labeled only if they differ significantly from their conventional counterparts, for example, if their nutritional content or potential to cause allergic reactions is altered.

With approval of the USDA Animal, Plant Health Inspection Service, over five hundred field trials have been safely conducted since 1987. About forty new agricultural products have completed all of the regulatory requirements and have been approved for sale.

Because genetic modification provides the capability to alter the inherited characteristics of an organism in a manner never before possible, it is seen as presenting both great opportunities and great risks. This dichotomy has generated a much debate from scientists, politicians and the public.

It is believed that on-going research in genetic engineering can hold the key to solving some of the world’s most significant problems. New products are being developed that have the potential to combat human disease, promote human health, reduce hunger, produce higher yields of food, combat animal disease and protect the environment.

Biotechnology can combat human disease through the use of more effective drugs and vaccines. It has led to the production of insulin for diabetes, interferon for the treatment of cancer, clot-busting enzymes for heart attack, as well as medicines for Parkinson's Alzheimer's, Aids and Leukemia.

Biotechnology can promote health in humans through production of nutritionally rich foods, such as grains, vegetables and fruits that contain more proteins, vitamins and minerals and less fatty acids.

It is estimated that biotechnology could reduce hunger by increasing crop productivity in the developing world by as much as twenty five percent. It could also help to prevent the post harvest loss of foods and grains, thereby increasing the amount of useable food produced. Many biotech crops may be able to grow under tougher growing conditions, such as drought, changing weather and nutrient-depleted soil.

Biotechnology is producing higher yields through crops with built-in protection from destructive insects, specific viral or fungal diseases and herbicide tolerance that allow for effective weed control with fewer herbicide applications. Biofertilizers, including nitrogen-fixing bacteria and some fungi, have the potential to provide nutrients to crops directly or to enhance the availability of soil nutrients to plants.

New products have been developed from biotechnology to combat animal disease. These include a vaccine that protects animals in the wild against rabies and a vaccine for "shipping fever," the major killer of beef cattle in feed lots.

Scientists are working to develop animal feeds that provide the nutritional requirements of livestock, or prevent or correct nutritional disorders.

By increasing the productivity of farmland now in use, biotechnology offers the potential to protect other areas of the environment, including rain forests and wetlands, from conversion to food production. Biotech crops can also help farmers protect the land and conserve natural resources through reduced irrigation and tillage that save topsoil from erosion, reduced fuel usage and less use of pesticides.

Many scientist and public citizens are concerned about potential long-term effects of genetically modification, which involves the crossing of species that do not occur in nature.
Some of the majors concerns are: escaped resistance into the environment, increase pesticide usage, introduction of allergens and toxins to food, antibiotic resistance and changes in food quality.

There is a concern that genes transplanted into pesticide-resistant crops may be spread unintentionally, by bird, insect or wind, from target crops to related weed species, creating a new class of "superweeds." Recently a field of canola, genetically modified to be resistant to an herbicide, cross-pollinated with a related weed species, resulting in a new strain of weed which was also resistant to the herbicide.

Another fear is that pesticide-resistant crops will cause an increase in the use of pesticides, which will find their way into the food and water supply. The widespread use of crops such as corn modified to include Bt, a safe natural pesticide, may also result in the development of Bt resistance in insects.

Many plants already contain small amounts of toxins. The modifications of the genetic make-up of plants, presents possibilities of unforeseen enhancement of natural toxins or the development of new toxins. An additional fear is that the genetic modification of foods might transfer allergens from other foods.

Scientists are not sure what impact eating large quantities of food with added vaccines and vitamins will have on young children. They also warn that inserted genes could change a food’s nutritional value and possibly crucial qualities, such as cancer-inhibiting abilities. They also fear that the process, used in some genetically modified products, of using antibiotic resistant bacteria as a gene marker, may add to increased antibiotic resistance and diminish the effectiveness of drugs.

One social issue poses the question of whether biotechnology will increase the prosperity gap, giving farmers in rich countries an unfair advantage over those in poorer countries. Additional issues ask if biotechnology may concentrate economic power with large multinational companies, erode rural communities and reduce biological diversity.

Combat Human Disease

Insulin, used in the treatment of diabetes, is the product of one of the first genetically enhanced organisms. Researchers found that they could generate a consistent, reliable and inexpensive source of insulin by inserting a human gene into the genetic code of a bacterium. Insulin has been produced this way since 1982.

Scientists are working on a banana that delivers the Hepatitis B vaccine orally. The cost could be less than ten cents a dose, and no medical personnel would be needed to administer the vaccine. Farmers could grow the vaccine right in their own communities, eliminating transportation and refrigeration problems.

Promote Human Health

As many as a hundred million children worldwide suffer from Vitamin A deficiency, a leading cause of blindness. Millions of women of childbearing age are iron deficient, placing their babies at risk of physical and mental retardation, premature birth and natal mortality. Scientists have developed a strain of "golden" rice that contains more iron and beta carotene, a precursor of Vitamin A. This dietary staple can be locally grown and will deliver the needed vitamins.
Scientists have also discovered a way to boost beta-carotene levels in canola, and are researching a more nutritious strain of cassava, the leading source of calories in Africa. Biotechnology may also make it possible to identify and remove known allergenic agents from foods.

Reduce Hunger

In 1999, the world population reached six billion; it could top nine billion by 2050. The world’s supply of usable farmland is shrinking, while the growing population requires more land. According to the U.N., eight hundred million people worldwide are already chronically malnourished. Biotechnology alone won't solve the problems of hunger and malnutrition, but it can play an important role, by increasing crop yields and decreasing spoilage.

Increased Crop Yield

Since the 1920s, the corn borer has been a major insect pest of corn. It destroys approximately seven percent, or forty million tons, of the world's corn crop every year. In North American the cost of the damage is said to exceed one billion dollars annually.

In field corn, the damage caused by borer larvae (caterpillars) reduces yields, causing harvesting difficulties because of broken corn stalks.
Sweet corn growers have traditionally protected their crops from corn borer, and a similar pest called corn ear worm by spraying with insecticides. Depending on the severity of the infestation, a field may be sprayed several times during the growing season.

Through genetic engineering, scientists have transferred genes from the common soil bacterium Bacillus thuringiensis (Bt) which has been used for years as an organic pesticide, into some corn hybrids as a means to control the European corn borer. Because Bt provides protection for the corn plant, use of insecticides for corn borer control can be reduced or eliminated.

Virus-resistant squash and papayas have been produced, and research is under way on virus-resistant sweet potatoes and other crops.
Biotechnology has been used to pinpoint genes that could help wheat and rice, major food staple, grow in areas that are now hostile to crops. An experimental potato hybrid contains genes to resist a virulent strain of the so-called "late blight."

Selective herbicides that affect only certain species or families of plants allow farmers to control a wide range of weeds with little risk to the crop. Researchers have developed genetically enhanced crops with resistance to non-selective herbicides, such as Roundup and Liberty, that kill almost all plants upon which they are sprayed. Previously non-selective herbicides could only be used before planting or after harvest or the crop would have been killed. These new herbicides are safer and less likely to leach into the ground water.

Chromosome: a structure found in the nucleus of cells. It contains DNA molecules tightly coiled around proteins, and is visible under the microscopes.

Gene: a small section of a chromosome. It controls (either singly or in coordination with other genes) the production of proteins. Some genes turn on and off other genes and are not involved in protein synthesis. Genes are found in all living organism.

DNA: Deoxyribonucleic acid is the molecule that makes up genes. It is found in all cells, usually in the nuclei, and is composed of six molecules: sugars, phosphates and four bases. The order in which these molecules are arranged determines the traits of a particular organism. DNA directs the growth, organization, development and function of cells, controlling the way characteristics, such as eye color, are passed on to the next generation. It is not visible under a microscope.

Proteins: are chains of amino acids. They perform the needed functions of living organisms. When a gene is "expressed", it is translated into protein.
A,C,G and T: Abbreviations for the chemical names of the individual components of DNA, adenine, cytosine, guanine and thymine. The order of these along a DNA chain is what controls cell functions.

Genotype: the DNA code that controls the characteristics of an organism

Phenotype: The visual measurable characteristics of an organism

Locus: the location of a gene on a chromosome

Genetic Modified Organism or transgenic: an organism that has been modified by genetic engineering to contain DNA from an external source.
Link:

Tuesday, June 5, 2007

Gd piece of Fsaf Article


Food Safety in the Kitchen

Food safety simply means producing food which is clean, safe and of good quality. Good food safety is important to prevent food poisoning.
Food poisoning can occur at any stage from storage of uncooked food, food preparation, cooking and storage of cooked food.
Here are some handy tips on what to do and what NOT to do to minimise the risk of food poisoning.

During food preparation and cooking…….

1. Wear waterproof gloves before preparing food.
2. Have 2 chopping boards in your kitchen – 1 for raw meat and 1 for vegetables because bacteria from raw meat can be transferred to bread or fruits like tomato if you use the same chopping board.
3. Do not let raw food come into contact with cooked food or ready-to-eat food and vegetables.
4. Thaw food in the cooler part of the refrigerator, not on the kitchen counter.
5. Do not reheat leftover food more than once as this may lead to bacteria contamination of the food. The food should also be reheated till the internal temperature reaches at least 85 degrees celcius.

During food storage….

1. Raw food should be placed below cooked food in the refrigerator.
2. Food should be stored below 3 degrees celcius in the refrigerator as bacteria grow best at room temperatures.
3. Do not place food on a table for more than 2 hours at room temperature as this is the ideal temperature for food-poisoning bacteria to grow.
Last but not least, good hygiene should always be at everyone’s fingertips. This includes NOT allowing pets into the kitchen. Kitchen surfaces should always be kept free from oil, spills and blood stains from raw meat or fish.

Make it a point to practice food safety in your kitchen today!

Quiz

1. It is alright to use the same chopping board for cutting raw meat and vegetables. True or False?

Ans: False. Bacteria thrives on raw meat thus, it is advisable to have 2 different chopping boards for raw meat and vegetables. This is to prevent any bacteria from contaminating the vegetables and cooked food.

2. Leftover food should not be reheated more than once. True or False?

Ans: True. Leftover food should not be reheated more than once as it can lead to bacteria contamination and the internal temperature of the food should reach at least 85 degrees celcius.

Harmful to mankind health?


Monday, June 4, 2007


ENVIRONMENTAL BENEFITS ASSOCIATED WITH GM CROPS:

Issue: Reduced Pesticide Usage

Reduced pesticide usage is one of the benefits of genetically modified crops that are pest resistant. Currently, genetically modified pest resistant crops include Bt cotton, Bt corn, Bt sweet corn, Bt potatoes, and virus resistant squash. These crops are able to resist certain pests and need fewer pesticide sprays. In the past, pesticide usage on cotton, sweet corn and potatoes has been very high with some of these crops requiring more than a dozen insecticide sprays per season. However, Bt sweet corn needs less than 15 percent of the insecticide sprays than does traditional varieties.

But Bt crops still do need some insecticide sprays. Bt is very selective and only controls some insects, and the protection provided by the Bt only protects against some pests. So while Bt crops are protected from the primary pests, control of secondary pests may sometimes require the use of insecticide sprays.

Issue: GM Crops Compliment Biological Control

One group of non-target organisms that need to be encouraged is the natural enemies of our crop pests. Natural enemies are composed of a wide array of parasitic and predatory insects and other arthropods. Control of crop pests by natural enemies is referred to as biological control. Universities, as well as Federal and State agencies has been working for many years to increase the effectiveness and reliance on biological control. Unfortunately, biological control cannot prevent crop damage in all circumstances and farmers often need to apply pesticide sprays.

When these sprays include non-selective insecticides, the natural enemy populations are often hurt more than the pest that needed controlling. The reason is that while the pesticide may kill both the pest and its natural enemies, by killing the pest it has also eliminated the food source that the natural enemy populations will need to recover. Because of this, it often takes much longer for the natural enemy populations to recover than the pest population. In the absence of natural enemies, pest populations are able to increase much more rapidly. This can result in greater reliance on pesticide sprays after the natural enemies are eliminated.

Genetically modified crops that produce their own plant pesticides are more compatible with biological control. The plant pesticides are more selective than most insecticide sprays.
In addition, because the need fewer pesticide applications, they preserve natural enemies populations and are more compatible with biological control.

Issue: Plant Pesticides Impact less on Non-target Organisms

Genetically modified plants that produce their own plant pesticides include Bt cotton, Bt corn, Bt sweet corn, and Bt potatoes. These plant pesticides are very selective, for example, the type of Bt in Bt corn only controls the caterpillars of some moths and butterflies. The type of Bt in Bt potatoes controls Colorado potato beetles. In addition, the Bt is inside the plant, so only insects that feed on the plant or plant parts are exposed to the plant pesticide. An exception to this is with the pollen from Bt corn which is wind blown. The Bt-corn pollen also contains the Bt toxin. It has been shown in the laboratory to reduce the survival of monarch caterpillars that have been feed on milkweed plants that were dusted with this pollen.

But it is important to keep in mind that these genetically modified crops that produce their own plant pesticides require fewer pesticide sprays. Most of the commonly used insecticide used on these crops are referred to as broad spectrum insecticides. They are generally as toxic to non-target organisms as they are to the target pest. Plants that produce their own plant pesticides are more selective in terms of controlling pests without damaging non-target organisms. Their impact on non-target organisms is further reduced because they require fewer broad spectrum pesticide sprays.

Issue: Increased Yields, Reducing the Need to Expand Agricultural Acreage

While the genetically modified crops on the market today do not increase yields. For example, the GM crops that produce their own plant pesticides do not yield more than traditional varieties, they just protect the plants from yield loss. Differences in yield do not represent the ability of the plant to produce more. In fact, in the absence of pests, these hybrids should have yields equal to comparable to traditional hybrids.

However, GM crops that increase yields are under development and the future looks very promising. Unless yield increases are able to keep in pace with population growth, more land will be need to be devoted to commercial agriculture. Current tends show that the amount of prime agricultural land available is decreasing. Crop yields may need to increase by 20 to 40 percent in the next 20 years in order feed an expanding population. Biotechnology provides some of the tools needed to continue to increase the yields of the world's important staple crops.

Issue: Some GM Crops May Reduce Soil Erosion

New herbicide resistant crops may help to reduce soil erosion. We need to prevent soil erosion in order to maintain farm sustainability and to reduce pollution of streams, rivers and wetlands. These crops are tolerant of certain non-selective herbicides such a Roundup™ or Liberty™. This allows the producer greater flexibility in terms of when to control weeds. Rather than using preemergence herbicides that may need to incorporated into the soil, these are applied over the crop and the weeds as they are actively growing. GM herbicide resistant crops are compatible with and encourage no-till agriculture.


ENVIRONMENTAL ISSUES ASSOCIATED WITH GM CROPS:

Issue: Herbicide Resistant Crops Possibly Becoming Weeds in Following Years

One environmental and agronomic issue associated with transgenic crops that have been developed to be resistant to broad spectrum insecticides, is that seeds left behind after harvest may sprout and become weeds the following years. For example, if a farmer uses Roundup Ready™ corn one year then Roundup Ready™ soybeans the next year, the Roundup herbicide will not control volunteer corn that is Roundup Ready™. As more corps are developed that are resistant to the same herbicides, this will become more problematic.

While this is true that if producers rotated among crops with the same type of herbicide tolerance that the volunteers from previous crops would become weeds, relying solely on a single type of herbicide year after year generally is not a good idea. Whether or not multiple crops are tolerant of the same herbicide, relying exclusively on the same herbicide for a long period of time will select for weeds as well as volunteers that tolerate the herbicide. With the example of Roundup Ready™ corn one year then Roundup Ready™ soybeans the next year, there are many available herbicides that can control Roundup Ready™ corn in Roundup Ready™ soybeans and visa versa.

Issue: Potential Gene Escape and Development of 'Superweeds'

One fear with the development of herbicide tolerant, viral resistant or insect resistant GM plants is that they will outcross with wild relatives resulting in superweeds that are more competitive. More competitive weeds are more difficult to control and may make weed management more complicated, expensive, all chemically intensive. Weeds that have a competitive advantage will produce more seeds and be serious in following years.

The potential for outcrossing with weeds exists when crops are grown in areas with weedy relatives that inter breed. In the US for example, we do not have weeds that interbreed with corn, soybeans or potato, so genes inserted into these plants have a negligible chance of escaping into weedy relatives. However, GM squash and canola varieties can interbreed with wild relatives in the US, so the potential for outcrossing with wild relatives and the effect that it may have on weed populations needs to studied and considered prior to GM crops receiving government approval for commercial production.

Issue: Impact on non-target organisms

There has been much media attention given to the potential impact of GM crops on non target organisms. An ideal pest control tactic would be one that controls the pest, but does not harm other non-target organisms in any way. Non-target organisms include all organisms except for the pest to be controlled, this includes mammals, fish, birds, reptiles, and other insects.

Examples of non-target insects to be protected include lady beetles, lacewings, and other insect predators, honey bees and other insect pollinators, and butterflies and other aesthetically pleasing insects.


Media attention has focused on Bt-corn and the impact that it may have on monarch butterflies. At one time, some believed that Bt plants would be the idea control of some crops pests, because only the pests that fed on the plant would ingest the toxin and the toxin is only toxic to some plant feeding insects. However, some Bt-corn plants have relative high levels of the Bt protein in their pollen, and pollen released from these plants may fall on other plants and be eaten by other insects that are not pests. In the case of the monarch caterpillars, pollen from the Bt corn drifts onto milkweed plants which are common in and near corn fields. As the monarch feeds on the milkweed leaves, it ingests the Bt pollen and some caterpillars are killed.

Effects on non-target organisms is and will continue to be an important issue. New GM crops will need to be evaluated for their potential effects on non targets. However, a double standard has arisen for regulating non target effects, one for insecticides and the other for GM crops. Many of the insecticides used today are considered broad spectrum, they kill a wide range of insects including beneficials. Many are classified as Restricted Use Pesticides due to their toxicity to fish, birds, or other wildlife. Relative to most insecticides on the market, Bt-crops are more selective and potentially less damaging to non-target organisms.

Issue : Development of Pest Resistance:

Widespread and intensive use of GM crops that are resistant to pests has the potential of selecting for pests that are resistant to the GM crops. While the possibility of pest developing resistance to GM crops like Bt corn is only a theory, pests have a long history of developing resistance to any pest management tactic that is used for a long period of time over a wide area.
The examples pests being able to overcome pest management strategies are too numerous to list! Consider the western corn rootworm beetle in Illinois and Indiana. For more than 20 years it was effectively controlled through the use of a corn-soybean rotation. The eggs that were laid one summer in a corn field would hatch the following year in what has become a soybean field. This pest had been a problem only with continuous corn. But it adapted. Now a portion of the female beetles lay their eggs in soybean fields and rootworms are now a serious problem in first-year corn in this area. Don't underestimate the ability of insect pests to adapt!

To counter the ability of pests to develop resistance, farmers are required to use resistant management strategies. For example, the required resistance management plan with Bt corn is to plant some acreage with non-Bt hybrids. This is called the refuge strategy. In it, non-Bt acreage on each farm serves as a refuge, allowing some Bt-susceptible corn borers to survive. Use of resistance management strategies are required and will delay or prevent the development of pest resistance.

Issue: Antibiotic Resistance Marker Genes

One concern that has been expressed is that the use antibiotic resistance marker genes in some transgenic crops may foster the development of antibiotic resistance by harmful microbes. There is a possibility that harmful microbes may be able to capture antibiotic resistance genes either in the field from transgenic crops or their decaying crop residues or when the transgenic grains are feed to livestock or other animals. Antibiotic resistance remains a serious issue confronting clinical medicine.

However, others argue that the type of antibiotic resistance markers that are used today are common in nature. In fact, the antibiotic resistance used does not provide resistance to most of the antibiotics used in clinical medicine.

Issue: Biodiversity

Many environmentalists, including farmers themselves, are very concerned about the loss of biodiversity. Although the increased adoption of conventionally bred crops has raised similar concerns, we want to make sure that we maintain the pool of genetic diversity needed for time the future. Scientists continue to work actively to preserve plant species through the preservation of genetic material (DNA). The science of biotechnology has dramatically increased our knowledge of how genes express themselves and highlighted the importance of preserving genetic material.

Another related concern relates to the narrow range of crops that farmers currently grow. There are only about 35 crops with significant world production. For example, if all farmers grew the same variety of corn, one unstoppable corn blight could easily destroy a huge amount of our corn production. This has been a concern with conventionally-bred crop varieties as well. Biotechnology can help in two ways. Crop varieties can be developed that are "disaster-resistant" much quicker than through conventional breeding. And biotechnology has the increased capability of developing multiple sub-species of the same crop, tailored to specific agronomic conditions and consumer needs, thereby reducing the chance of an entire corn crop being wiped out.

In addition, because some biotech crops produce their own plant pesticides and reduce pesticide sprays, the potential non-target effects of these pesticides on other organisms is reduced. A concern with traditional pesticide applications has been the movement of pesticides out of the field through movement of soil and water. GM crops can lessen this concern.

Link:
http://www.ca.uky.edu/brei/Environment/environm.htm

Identification of Foodborne Baterial Pathogens by Gene Probes

Probes and Their Targets
Campylobacter jejuni: Ribosomal RNA

A probe that is specific for C. jejuni ribosomal RNA genes has been developed (86,87) and is available commercially. A pool of randomly selected and tested chromosomal fragments is also specific for C. jejuni, but the target has not been reported (83).

Escherichia coli: Heat-labile enterotoxin genes

The heat-labile enterotoxins (LT) of E. coli are a closely related group of proteins; they are distinguished from heat-stable enterotoxins (ST) by being immunogenic and are inactivated by heating at 60°C for 10 Min (31). The toxins stimulate adenylate cyclase (30) and can be detected by tissue culture assays of Chinese hamster ovary cells (30) or mouse Y-l adrenal cells (13). Using these tests, So et al. (102) localized and cloned the structural gene for LT; Dallas et al. (8) recloned a smaller fragment into plasmid pEWD299. Although there are several different genes for LT, as evidenced by their nucleotide sequences (56,73,103,110,111), they all share a significant amount of genetic similarity. The region of the LT genes chosen as a gene probe target is identical in each of these genes, so that all strains with the genetic potential to produce LTs should be detected.
The LT probe, eltA11, is a 20 base synthetic oligonucleotide that encodes amino acids 45-51 of the A subunit of the E. coli LT (111).

E. coli: Heat-stable enterotoxin genes

The heat-stable enterotoxin (ST) of E. coli is distinguished from LT (above) by heat stability and lack of immunogenicity. It can be detected by the suckling mouse bioassay (12) and acts by stimulating guanylate cyclase (22). There are at least two different types: ST I (also known as STa and STP) and ST II (also known as STb and STH). The latter toxin is not active in the infant mouse assay. These genes have been cloned and the nucleotide sequences of the region encoding STa and STb have been determined (74,82,101).
The STP probe is a 22 base synthetic oligonucleotide for the toxin type strain first isolated from pigs. It targets the region of the gene that encodes amino acids 4-12 of the toxin protein.
The STH probe is targeted to the ST elaborated by a strain of E. coli isolated from a human. The probe is also 22 bases long and targets the region of the STH that encodes amino acids 19-26 of the toxin.
Both of these probes have been tested for their specificity, and data are available on their ability to detect a few ST-producing cells against a high level of ST-negative microorganisms (35). The reliability of the colony hybridization technique with oligonucleotide probes was tested by collaborative study, using pure cultures of strains harboring the STH or STP genes (36).

Enteroinvasive Escherichia coli (EIEC) and Shigella: Invasive gene

Some strains of E. coli invade colonic epithelial cells, multiply intracellularly, and spread intercellularly, causing a dysenteric enteritis similar to that caused by Shigella (15). However, an important difference is that the infectious dose for Shigella may be as low as 1-10 organisms, whereas 108 EIEC cells are necessary to cause disease. A number of genetic determinants that encode virulence factors of EIEC and Shigella spp. are located on a large [220 kilobase (kb) pair] invasion plasmid (96). Loss of this virulence plasmid renders the bacterium avirulent (97). A 17 kb EcoRI fragment was used as a hybridization probe to detect invasive Shigella species and EIEC (4).
Small and Falkow (100) demonstrated that a 2.5 kb pair HindIII fragment of the large plasmid is required for invasion of human epithelial cells. Plasmid DNA involved in the invasion of HeLa cells by S. flexneri has also been cloned (61). These regions of the plasmid have been sequenced and are genetically similar (54). A probe from this region of the plasmid is specific for tissue culture cell-invasive EIEC and Shigella. Such probes also identify strains that are invasive in the guinea pig eye assay (98). Of 41 probe-positive isolates tested by the guinea pig method, 2 were negative, indicating that a few strains may be invasive in tissue culture assays but not in tests that require a greater number of pathogenic determinants (108). A synthetic probe of 18 bases has been constructed. Its target is within a gene that encodes for a virulence factor.

Enterohemorrhagic E. coli (EHEC): Shiga-like toxin (SLT) genes

Human illnesses ranging from simple diarrhea to hemorrhagic colitis and hemorrhagic uremic syndrome have been associated with strains of E. coli that produce moderate to high levels of Shiga-like toxins (SLTs). Strains of E. coli serotype O157:H7 are the most significant pathogens associated with hemorrhagic colitis; strains of serotype O26:H11 are also classified as EHEC. More than 50 other serotypes of E. coli that produce SLTs have been identified, but the correlation of these serotypes with disease is uncertain. Two related but distinct cytotoxins, SLT I and SLT II, have been characterized. Individual strains produce one or both cytotoxins. For example, E. coli O157:H7 produces SLT I, SLT II, or both, whereas O26:H11 produces only SLT I. The DNA sequences of SLT I and SLT II structural genes have been published, and analysis shows that SLT I has 99% homology with the Shiga toxin gene of S. dysenteriae type 1, but SLT II has only 60% homology (41). Two synthetic oligodeoxyribonucleotide probes were prepared from sequence data from the A-subunit regions of the SLT I and SLT II genes (nucleotides 473-490 and 472-490, respectively). HC agar (M62) (see ref. 105) was the selective medium chosen to screen isolates and foods for E. coli strains that carry the SLT gene because the growth of E. coli O157:H7 is less inhibited on HC agar than on other selective media. HC agar contains NaCl and a lower concentration of bile salts No. 3. Its plating efficiency of a strain of E. coli O157:H7 at 37 and 43°C for 17 h was similar to that of plate count agar. Plating efficiencies of other E. coli serotypes that carry the SLT gene have not been determined. The modified enrichment procedure of Doyle and Schoeni (14) is included in the method for detection of low level contamination of foods. For additional information about enterohemorrhagic strains of E. coli, see the review by Karmali (46).

Enterohemorrhagic E. coli (EHEC): O157:H7 serotype-specific probe

The fluorogenic MUG assay for E. coli is based on the activity of the -glucuronidase (GUD) enzyme, which is encoded by the uidA gene in E. coli. Although isolates of serotype O157:H7 are negative with the MUG assay, genetic studies have shown that this EHEC serogroup also contains uidA gene sequences for the GUD enzyme (21). Sequencing analysis has determined that the uidA gene of O157:H7 serotype contains several base mutations; therefore, it is not identical to the uidA gene of MUG assay (+) E. coli. Although the base mutations in the uidA allele of O157:H7 do not appear to be responsible for the absence of the MUG phenotype, one of the base changes was found to be conserved among the O157:H7 serogroup. An oligonucleotide probe, PF-27, directed to this base alteration was developed and determined to be specific only for EHEC isolates of serotype O157:H7. Other SLT-producing EHEC and other pathogenic E coli or enteric bacteria failed to hybridize with PF-27 (20).

Listeria monocytogenes: Invasion-associated protein (iap) and hemolysin (hly) genes

Of the seven Listeria species that have been isolated from a variety of foods, including dairy, vegetable, meat, and poultry products, only L. monocytogenes has been implicated in human disease. Genetic and physiological studies have incriminated an extracellular hemolysin as one of the virulence factors in L. monocytogenes (5,26,47). This hemolysin (also called listeriolysin O or alpha-listeriolysin) has been cloned and sequenced (11,55,64). Several oligonucleotides (including AD13) were constructed by using the sequence of the listeriolysin O gene (64) and can specifically identify L. monocytogenes in foods by colony hybridization (11,70).
A 5.3 kb DNA fragment encoding a 60 kilodalton (Kdal) protein (msp) associated with hemolytic activity has been cloned (24). Kuhn and Goebel (53) reported the cloning and sequencing of a gene (iap) whose product (a 60 Kdal protein) may be involved in the uptake of L. monocytogenes by nonprofessional phagocytes. Sequence analysis revealed that the msp and iap share extensive homology, which indicates that msp and iap may be the same gene (51). An internal region of this gene was sequenced (Datta, unpublished results) and a synthetic probe, AD07, was used to identify and enumerate L. monocytogenes in a number of foods (9,10,34). Thus, either AD07 (for the iap gene) or AD13 (for the hly gene) can be used to detect and enumerate L. monocytogenes in foods. To avoid false-negative results because of "silent" mutations in the gene (nucleotide changes that affect DNA probe binding but do not change the gene function), both probes should be used in combination (designated AD713).

Salmonella species:

Originally, several restriction endonuclease fragments selected randomly from the Salmonella chromosome were used as probes to identify members of the genus (23). Although these molecules served as specific probes, the role played by the target genes was never reported. More recently, probes were developed for regions of the bacterial ribosomal gene that are unique for salmonellae. These probes were used to develop a commercial kit that also uses a nonisotopic labeling and detection system (7).

Staphylococcus aureus: entB probe

Six groups (A, B, C1, C2, D, and E) of related enterotoxins associated with pathogenicity are elaborated by some strains of S. aureus and can cause symptoms of staphylococcal food poisoning if ingested (1). The genes for enterotoxins A, B, C1, and E (entA, entB, entC1, and entE) have been cloned and sequenced (2,3,6,43,85).
Three synthetic oligonucleotide probes were synthesized according to the sequence of the entB gene and used to test 210 strains of S. aureus (78). One probe was specific for entB; the others hybridized with strains producing enterotoxin C. The former probe was used to detect EntB-producing S. aureus in artificially contaminated crabmeat (Trucksess and Williams, manuscript in preparation). Although the nucleotide sequences of enterotoxin genes for groups A, C1, and E are known, synthetic probes have not been reported.

Vibrio cholerae: Cholera toxin

The classical cholera enterotoxin (CT) is a major virulence factor in pathogenic strains of V. cholerae. The mechanism of action and immunological reactivity is quite similar to the LT of E. coli. Genes encoding this multisubunit protein were cloned and sequenced (57,58,63). Non-O1 V. cholerae enterotoxin genes are apparently similar to classical CT (33). Two sequences from the A subunit structural gene for production of the classical enterotoxin are used as probes to detect the CT gene: ctxA11 (bases 702-721) and ctxA12 (bases 718-735).

Vibrio parahaemolyticus: Thermostable direct hemolysin

An important foodborne pathogen often associated with seafood, V. parahaemolyticus can produce a thermostable direct hemolysin (TDH) (95), also referred to as the Kanagawa phenomenon-associated hemolysin (69). This phenotype is commonly associated with strains isolated from humans with gastroenteritis but rarely found in environmental isolates (44). It is not yet known if this hemolysin is a virulence factor, but epidemiological evidence suggests that it is. The gene for the hemolysin has been cloned and sequenced (45,75,106). The specificity of both the cloned probes (76) and a synthetic oligonucleotide probe, tdh3 (77) has been established. The tdh3 probe is 18 bases long and its target encodes amino acids 122-128 of the tdh gene.

Vibrio vulnificus: Cytotoxin/hemolysin

V. vulnificus has been implicated as a cause of human infections and septicemia. The primary source of infection appears to be raw or undercooked seafood, especially raw oysters (71). This lactose-positive vibrio produces a cytotoxin/hemolysin which was implicated as a virulence factor (28), and the gene has been cloned (109). A 3.2 kb DNA fragment carrying the structural gene for this protein is a specific probe for V. vulnificus (72) and has been sequenced (112). One synthetic probe (VV6) exhibited 100% specific for 166 laboratory and environmental strains of V. vulnificus (FDA Contract No. 223-84-2031, Task XIII).

Yersinia pseudotuberculosis: Invasive gene (INV-3)

A chromosomal gene of Y. pseudotuberculosis, inv, which plays an integral part in Yersinia pathogenicity, has been cloned and sequenced (38,39). Oligonucleotide probe INV-3, based on published inv sequence (39) is 21 nucleotide bases long and targeted to a region 200 base pairs away from the 5' terminus of the inv gene of Y. pseudotuberculosis (19). Tests of INV-3 using Southern and colony hybridizations were compared with HeLa cell invasion studies and shown to be specific only for invasive Y. pseudotuberculosis isolates. Although there are homologous sequences between the inv genes of Y. enterocolitica and Y. pseudotuberculosis, this homology is not detectable by INV-3.

Yersinia enterocolitica: Chromosomal invasion gene (PF-13)

The genes responsible for mammalian cell invasion are also carried on the chromosome in Y. enterocolitica (66). Unlike Y. pseudotuberculosis, however, Y. enterocolitica has two loci that encode the invasion phenotype. The inv locus, homologous to the inv gene of Y. pseudotuberculosis, allows high level invasion of several tissue culture cell lines, whereas the ail gene shows more host specificity (66). Analysis of Yersinia serotypes and species using cloned probes from inv and ail showed that all disease-causing isolates are tissue culture-invasive; all these isolates reacted with the AIL gene probe (67). The INV probe reacted with both tissue culture-invasive and noninvasive isolates; however, recent evidence suggests that the inv in these noninvasive strains may not be expressed. The oligonucleotide probe PF13 is targeted specifically to a region 60 base pairs away from the 3' terminus of the ail gene of Y. enterocolitica. The probe is 18 nucleotides in length. A comparison of colony and Southern hybridization studies of 150 yersiniae and non-yersiniae isolates and HeLa cell invasion studies showed that PF13 hybridized only with invasive Y. enterocolitica isolates (19).

Yersinia enterocolitica: Plasmid gene (SP-12)

All pathogenic Yersinia species carry a 42-48 Mdal plasmid (pYV), which encodes for many of the virulence-associated phenotypes (84). These include Ca2+-dependent growth, mouse lethality, cytotoxicity, Sereny reaction, production of V and W antigens, serum resistance, and production of outer membrane proteins (YOPs). The pYV plasmid of Y. enterocolitica was subcloned and the region encoding for HEp-2 cell cytotoxicity and Sereny reaction was identified and sequenced (91). A 24 base oligonucleotide probe, SP12, targeted to this region was shown to be specific for the virulence plasmid. The use of SP12 for detecting pathogenic Y. enterocolitica isolates in artificially inoculated foods was also evaluated (65).
For more reading plaesure:

Safety of GM food? [UNKNOWN]

How safe is GM Food?

(Find out more in
the previous & next few blogs)






How GM Crop is produced?

The "Genes Trnasferring" Process..

ORange w KIwi Fruit

How abt a taste of an orange w Kiwi fruit? New "product" from modern Technology.. E.g. of GM Food..

Qs on GM Foods?


20 QUESTIONS ON GENETICALLY MODIFIED (GM) FOODS

Q1. What are genetically modified (GM) organisms and GM foods?

These questions and answers have been prepared by WHO in response to questions and concerns by a number of WHO Member State Governments with regard to the nature and safety of genetically modified food.

Genetically modified organisms (GMOs) can be defined as organisms in which the genetic material (DNA) has been altered in a way that does not occur naturally. The technology is often called “modern biotechnology” or “gene technology”, sometimes also “recombinant DNA technology” or “genetic engineering”. It allows selected individual genes to be transferred from one organism into another, also between non-related species.
Such methods are used to create GM plants – which are then used to grow GM food crops.

Q2. Why are GM foods produced?

GM foods are developed – and marketed – because there is some perceived advantage either to the producer or consumer of these foods. This is meant to translate into a product with a lower price, greater benefit (in terms of durability or nutritional value) or both. Initially GM seed developers wanted their products to be accepted by producers so have concentrated on innovations that farmers (and the food industry more generally) would appreciate.

The initial objective for developing plants based on GM organisms was to improve crop protection. The GM crops currently on the market are mainly aimed at an increased level of crop protection through the introduction of resistance against plant diseases caused by insects or viruses or through increased tolerance towards herbicides.
Insect resistance is achieved by incorporating into the food plant the gene for toxin production from the bacterium Bacillus thuringiensis (BT). This toxin is currently used as a conventional insecticide in agriculture and is safe for human consumption. GM crops that permanently produce this toxin have been shown to require lower quantities of insecticides in specific situations, e.g. where pest pressure is high.

Virus resistance is achieved through the introduction of a gene from certain viruses which cause disease in plants. Virus resistance makes plants less susceptible to diseases caused by such viruses, resulting in higher crop yields.

Herbicide tolerance is achieved through the introduction of a gene from a bacterium conveying resistance to some herbicides. In situations where weed pressure is high, the use of such crops has resulted in a reduction in the quantity of the herbicides used.

Q3. Are GM foods assessed differently from traditional foods?

Generally consumers consider that traditional foods (that have often been eaten for thousands of years) are safe. When new foods are developed by natural methods, some of the existing characteristics of foods can be altered, either in a positive or a negative way National food authorities may be called upon to examine traditional foods, but this is not always the case. Indeed, new plants developed through traditional breeding techniques may not be evaluated rigorously using risk assessment techniques.

With GM foods most national authorities consider that specific assessments are necessary. Specific systems have been set up for the rigorous evaluation of GM organisms and GM foods relative to both human health and the environment. Similar evaluations are generally not performed for traditional foods. Hence there is a significant difference in the evaluation process prior to marketing for these two groups of food.

One of the objectives of the WHO Food Safety Programme is to assist national authorities in the identification of foods that should be subject to risk assessment, including GM foods, and to recommend the correct assessments.

Q4. How are the potential risks to human health determined?

The safety assessment of GM foods generally investigates: (a) direct health effects (toxicity), (b) tendencies to provoke allergic reaction (allergenicity); (c) specific components thought to have nutritional or toxic properties; (d) the stability of the inserted gene; (e) nutritional effects associated with genetic modification; and (f) any unintended effects which could result from the gene insertion.

Q5. What are the main issues of concern for human health?

While theoretical discussions have covered a broad range of aspects, the three main issues debated are tendencies to provoke allergic reaction (allergenicity), gene transfer and outcrossing.

Allergenicity. As a matter of principle, the transfer of genes from commonly allergenic foods is discouraged unless it can be demonstrated that the protein product of the transferred gene is not allergenic.
While traditionally developed foods are not generally tested for allergenicity, protocols for tests for GM foods have been evaluated by the Food and Agriculture Organization of the United Nations (FAO) and WHO. No allergic effects have been found relative to GM foods currently on the market.

Gene transfer. Gene transfer from GM foods to cells of the body or to bacteria in the gastrointestinal tract would cause concern if the transferred genetic material adversely affects human health. This would be particularly relevant if antibiotic resistance genes, used in creating GMOs, were to be transferred. Although the probability of transfer is low, the use of technology without antibiotic resistance genes has been encouraged by a recent FAO/WHO expert panel.
Outcrossing.
The movement of genes from GM plants into conventional crops or related species in the wild (referred to as “outcrossing”), as well as the mixing of crops derived from conventional seeds with those grown using GM crops, may have an indirect effect on food safety and food security. This risk is real, as was shown when traces of a maize type which was only approved for feed use appeared in maize products for human consumption in the United States of America. Several countries have adopted strategies to reduce mixing, including a clear separation of the fields within which GM crops and conventional crops are grown.
Feasibility and methods for post-marketing monitoring of GM food products, for the continued surveillance of the safety of GM food products, are under discussion.

Q6. How is a risk assessment for the environment performed?

Environmental risk assessments cover both the GMO concerned and the potential receiving environment. The assessment process includes evaluation of the characteristics of the GMO and its effect and stability in the environment, combined with ecological characteristics of the environment in which the introduction will take place. The assessment also includes unintended effects which could result from the insertion of the new gene.

Q7. What are the issues of concern for the environment?

Issues of concern include: the capability of the GMO to escape and potentially introduce the engineered genes into wild populations; the persistence of the gene after the GMO has been harvested; the susceptibility of non-target organisms (e.g. insects which are not pests) to the gene product; the stability of the gene; the reduction in the spectrum of other plants including loss of biodiversity; and increased use of chemicals in agriculture. The environmental safety aspects of GM crops vary considerably according to local conditions.

Current investigations focus on: the potentially detrimental effect on beneficial insects or a faster induction of resistant insects; the potential generation of new plant pathogens; the potential detrimental consequences for plant biodiversity and wildlife, and a decreased use of the important practice of crop rotation in certain local situations; and the movement of herbicide resistance genes to other plants.

Q8. Are GM foods safe?

Different GM organisms include different genes inserted in different ways. This means that individual GM foods and their safety should be assessed on a case-by-case basis and that it is not possible to make general statements on the safety of all GM foods.

GM foods currently available on the international market have passed risk assessments and are not likely to present risks for human health. In addition, no effects on human health have been shown as a result of the consumption of such foods by the general population in the countries where they have been approved. Continuous use of risk assessments based on the Codex principles and, where appropriate, including post market monitoring, should form the basis for evaluating the safety of GM foods.

Q9. How are GM foods regulated nationally?

The way governments have regulated GM foods varies. In some countries GM foods are not yet regulated. Countries which have legislation in place focus primarily on assessment of risks for consumer health. Countries which have provisions for GM foods usually also regulate GMOs in general, taking into account health and environmental risks, as well as control- and trade-related issues (such as potential testing and labelling regimes). In view of the dynamics of the debate on GM foods, legislation is likely to continue to evolve.

Q10. What kind of GM foods are on the market internationally?

All GM crops available on the international market today have been designed using one of three basic traits: resistance to insect damage; resistance to viral infections; and tolerance towards certain herbicides. All the genes used to modify crops are derived from microorganisms.

Q11. What happens when GM foods are traded internationally?

No specific international regulatory systems are currently in place. However, several international organizations are involved in developing protocols for GMOs.

The Codex Alimentarius Commission (Codex) is the joint FAO/WHO body responsible for compiling the standards, codes of practice, guidelines and recommendations that constitute the Codex Alimentarius: the international food code. Codex is developing principles for the human health risk analysis of GM foods. The premise of these principles dictates a premarket assessment, performed on a case-by-case basis and including an evaluation of both direct effects (from the inserted gene) and unintended effects (that may arise as a consequence of insertion of the new gene). The principles are at an advanced stage of development and are expected to be adopted in July 2003. Codex principles do not have a binding effect on national legislation, but are referred to specifically in the Sanitary and Phytosanitary Agreement of the World Trade Organization (SPS Agreement), and can be used as a reference in case of trade disputes.

The Cartagena Protocol on Biosafety (CPB), an environmental treaty legally binding for its Parties, regulates transboundary movements of living modified organisms (LMOs). GM foods are within the scope of the Protocol only if they contain LMOs that are capable of transferring or replicating genetic material. The cornerstone of the CPB is a requirement that exporters seek consent from importers before the first shipment of LMOs intended for release into the environment. The Protocol will enter into force 90 days after the 50th country has ratified it, which may be in early 2003 in view of the accelerated depositions registered since June 2002.

Q12. Have GM products on the international market passed a risk assessment?

The GM products that are currently on the international market have all passed risk assessments conducted by national authorities. These different assessments in general follow the same basic principles, including an assessment of environmental and human health risk. These assessments are thorough, they have not indicated any risk to human health.

Q13. Why has there been concern about GM foods among some politicians, public interest groups and consumers, especially in Europe?

Since the first introduction on the market in the mid-1990s of a major GM food (herbicide-resistant soybeans), there has been increasing concern about such food among politicians, activists and consumers, especially in Europe. Several factors are involved.

In the late 1980s – early 1990s, the results of decades of molecular research reached the public domain. Until that time, consumers were generally not very aware of the potential of this research. In the case of food, consumers started to wonder about safety because they perceive that modern biotechnology is leading to the creation of new species.

Consumers frequently ask, “what is in it for me?”. Where medicines are concerned, many consumers more readily accept biotechnology as beneficial for their health (e.g. medicines with improved treatment potential). In the case of the first GM foods introduced onto the European market, the products were of no apparent direct benefit to consumers (not cheaper, no increased shelf-life, no better taste). The potential for GM seeds to result in bigger yields per cultivated area should lead to lower prices. However, public attention has focused on the risk side of the risk-benefit equation.

Consumer confidence in the safety of food supplies in Europe has decreased significantly as a result of a number of food scares that took place in the second half of the 1990s that are unrelated to GM foods. This has also had an impact on discussions about the acceptability of GM foods. Consumers have questioned the validity of risk assessments, both with regard to consumer health and environmental risks, focusing in particular on long-term effects. Other topics for debate by consumer organizations have included allergenicity and antimicrobial resistance. Consumer concerns have triggered a discussion on the desirability of labelling GM foods, allowing an informed choice. At the same time, it has proved difficult to detect traces of GMOs in foods: this means that very low concentrations often cannot be detected.

Q14. How has this concern affected the marketing of GM foods in the European Union?

The public concerns about GM food and GMOs in general have had a significant impact on the marketing of GM products in the European Union (EU). In fact, they have resulted in the so-called moratorium on approval of GM products to be placed on the market. Marketing of GM food and GMOs in general are the subject of extensive legislation. Community legislation has been in place since the early 1990s. The procedure for approval of the release of GMOs into the environment is rather complex and basically requires agreement between the Member States and the European Commission. Between 1991 and 1998, the marketing of 18 GMOs was authorized in the EU by a Commission decision.

As of October 1998, no further authorizations have been granted and there are currently 12 applications pending. Some Member States have invoked a safeguard clause to temporarily ban the placing on the market in their country of GM maize and oilseed rape products. There are currently nine ongoing cases. Eight of these have been examined by the Scientific Committee on Plants, which in all cases deemed that the information submitted by Member States did not justify their bans.

During the 1990s, the regulatory framework was further extended and refined in response to the legitimate concerns of citizens, consumer organizations and economic operators (described under Question 13). A revised directive will come into force in October 2002. It will update and strengthen the existing rules concerning the process of risk assessment, risk management and decision-making with regard to the release of GMOs into the environment. The new directive also foresees mandatory monitoring of long-term effects associated with the interaction between GMOs and the environment.

Labelling in the EU is mandatory for products derived from modern biotechnology or products containing GM organisms. Legislation also addresses the problem of accidental contamination of conventional food by GM material. It introduces a 1% minimum threshold for DNA or protein resulting from genetic modification, below which labelling is not required.

In 2001, the European Commission adopted two new legislative proposals on GMOs concerning traceability, reinforcing current labelling rules and streamlining the authorization procedure for GMOs in food and feed and for their deliberate release into the environment.

The European Commission is of the opinion that these new proposals, building on existing legislation, aim to address the concerns of Member States and to build consumer confidence in the authorization of GM products. The Commission expects that adoption of these proposals will pave the way for resuming the authorization of new GM products in the EU.

Q15. What is the state of public debate on GM foods in other regions of the world?

The release of GMOs into the environment and the marketing of GM foods have resulted in a public debate in many parts of the world. This debate is likely to continue, probably in the broader context of other uses of biotechnology (e.g. in human medicine) and their consequences for human societies. Even though the issues under debate are usually very similar (costs and benefits, safety issues), the outcome of the debate differs from country to country. On issues such as labelling and traceability of GM foods as a way to address consumer concerns, there is no consensus to date. This has become apparent during discussions within the Codex Alimentarius Commission over the past few years. Despite the lack of consensus on these topics, significant progress has been made on the harmonization of views concerning risk assessment. The Codex Alimentarius Commission is about to adopt principles on premarket risk assessment, and the provisions of the Cartegena Protocol on Biosafety also reveal a growing understanding at the international level.

Most recently, the humanitarian crisis in southern Africa has drawn attention to the use of GM food as food aid in emergency situations. A number of governments in the region raised concerns relating to environmental and food safety fears. Although workable solutions have been found for distribution of milled grain in some countries, others have restricted the use of GM food aid and obtained commodities which do not contain GMOs.

Q16. Are people’s reactions related to the different attitudes to food in various regions of the world?

Depending on the region of the world, people often have different attitudes to food. In addition to nutritional value, food often has societal and historical connotations, and in some instances may have religious importance. Technological modification of food and food production can evoke a negative response among consumers, especially in the absence of good communication on risk assessment efforts and cost/benefit evaluations.

Q17. Are there implications for the rights of farmers to own their crops?

Yes, intellectual property rights are likely to be an element in the debate on GM foods, with an impact on the rights of farmers. Intellectual property rights (IPRs), especially patenting obligations of the TRIPS Agreement (an agreement under the World Trade Organization concerning trade-related aspects of intellectual property rights) have been discussed in the light of their consequences on the further availability of a diversity of crops. In the context of the related subject of the use of gene technology in medicine, WHO has reviewed the conflict between IPRs and an equal access to genetic resources and the sharing of benefits. The review has considered potential problems of monopolization and doubts about new patent regulations in the field of genetic sequences in human medicine. Such considerations are likely to also affect the debate on GM foods.

Q18. Why are certain groups concerned about the growing influence of the chemical industry on agriculture?

Certain groups are concerned about what they consider to be an undesirable level of control of seed markets by a few chemical companies. Sustainable agriculture and biodiversity benefit most from the use of a rich variety of crops, both in terms of good crop protection practices as well as from the perspective of society at large and the values attached to food. These groups fear that as a result of the interest of the chemical industry in seed markets, the range of varieties used by farmers may be reduced mainly to GM crops. This would impact on the food basket of a society as well as in the long run on crop protection (for example, with the development of resistance against insect pests and tolerance of certain herbicides).
The exclusive use of herbicide-tolerant GM crops would also make the farmer dependent on these chemicals. These groups fear a dominant position of the chemical industry in agricultural development, a trend which they do not consider to be sustainable.

Q19. What further developments can be expected in the area of GMOs?

Future GM organisms are likely to include plants with improved disease or drought resistance, crops with increased nutrient levels, fish species with enhanced growth characteristics and plants or animals producing pharmaceutically important proteins such as vaccines. At the international level, the response to new developments can be found in the expert consultations organized by FAO and WHO in 2000 and 2001, and the subsequent work of the Codex ad hoc Task Force on Foods Derived from Biotechnology. This work has resulted in an improved and harmonized framework for the risk assessment of GM foods in general. Specific questions, such as the evaluation of allergenicity of GM foods or the safety of foods derived from GM microorganisms, have been covered and an expert consultation organized by FAO and WHO will focus on foods derived from GM animals in 2003.

Q20. What is WHO doing to improve the evaluation of GM foods?

WHO will take an active role in relation to GM foods, primarily for two reasons:
(1) on the grounds that public health could benefit enormously from the potential of biotechnology, for example, from an increase in the nutrient content of foods, decreased allergenicity and more efficient food production; and
(2) based on the need to examine the potential negative effects on human health of the consumption of food produced through genetic modification, also at the global level. It is clear that modern technologies must be thoroughly evaluated if they are to constitute a true improvement in the way food is produced. Such evaluations must be holistic and all-inclusive, and cannot stop at the previously separated, non-coherent systems of evaluation focusing solely on human health or environmental effects in isolation.

Work is therefore under way in WHO to present a broader view of the evaluation of GM foods in order to enable the consideration of other important factors. This more holistic evaluation of GM organisms and GM products will consider not only safety but also food security, social and ethical aspects, access and capacity building. International work in this new direction presupposes the involvement of other key international organizations in this area. As a first step, the WHO Executive Board will discuss the content of a WHO report covering this subject in January 2003. The report is being developed in collaboration with other key organizations, notably FAO and the United Nations Environment Programme (UNEP). It is hoped that this report could form the basis for a future initiative towards a more systematic, coordinated, multi-organizational and international evaluation of certain GM foods.
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